>The question is how much to we want to break working pages/content? For example, if I thought that were feasible, I would >specify that no space followed commas, e.g., rgb(0,0,0) instead of rgb(0, 0, 0).
>However, my understanding of the goals of CSSOM is that, all things considered, it should try to capture current practice >when it appears there is significant consensus towards a common behavior. At present, that common behavior seems use rgb() >rather than rgba() for opaque colors.
Code that handles both correctly wouldn't be affected by choosing one result over the other. And new code would be simpler.
You're of course right about code that assumes rgb() strings: that could suddenly start breaking.